Re: [PATCH/RFC] Add node 'states' sysfs class attribute - V2

["Nish Aravamudan" <nish.aravamudan@gmail.com>]

On 8/28/07, Christoph Lameter <clameter@sgi.com> wrote:
> On Tue, 28 Aug 2007, Lee Schermerhorn wrote:
>
> > I thought I'd give it a try, but thinking that /proc variables were
> > discouraged, where else but sysfs to put them.  A class attribute
> > to /sys/devices/system/node seemed like the appropriate place.
>
> Right. That is the right place.
>
> > I'm not wedded to this interface.  However, I realy don't think it's
> > worth doing as multiple files.
>
> I think one single file per nodemask makes sense. Otherwise files become
> difficult to parse. I just forgot....
>
> > its executed, in the grand scheme of things.  However, I must admit that
> > I've become addicted to the ease with which one can write one-off
> > scripts to query configuration/statistics, tune/modify behavior or
> > trigger actions via just cat'ing from and/or echo'ing to a /proc or /sys
> > file.
> >
> > So, where to go with this patch?  Drop it?  Leave it as is?  Move
> > it /proc so that it can be a single file?   Make it multiple files in
> > sysfs?  Putting it as politely as possible, the last is not my favorite
> > option, but if folks think this info is useful and that's the way to go,
> > so be it.  And what about mask vs list?  It's a 4 character change in
> > the code to go either way.
>
> I would suggest to do the one file thing in sysfs and use the function
> that already exists in the kernel to print the nice nodelists. Using the
> nice function is just calling another function since the code is already
> there.
>
> At some point we may even allow changing the nodemasks. One could imagine
> that we would add nodemasks that allow use of hugepages on certain nodes
> or the slab allocator to allocate on certain nodes.

Just to chime in here -- I've been on vacation for a bit recently -- I
fully support the one-value per file rule for sysfs. I think it makes
things a bit clearer. I like this attribute as well, and the idea of
expanding it down the road is easiest if we use one file per-nodemask.

Thanks,
Nish

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